Endoscopic Sacroiliac Joint Rhizotomy

The sacroiliac joints sit on either side of the base of the spine, joining the sacrum to the pelvis. They carry and transfer load between the spine and the legs, and when a joint becomes painful — through wear, injury, altered mechanics after a fusion, or inflammation — it typically produces pain low down and to one side, in the buttock and sometimes down the back of the leg. SI joint pain is frequently mistaken for disc or facet pain, so the key to treating it well is proving the joint is the source, usually with diagnostic injections that temporarily numb it. Only if the pain reliably switches off with the test does a rhizotomy make sense.

The back of the sacroiliac joint is supplied by a set of small nerve twigs called the lateral branches, which carry its pain signals. A rhizotomy interrupts these lateral branches so they can no longer carry pain from the joint. The established way to do this is radiofrequency ablation — heating the nerves through needles placed under x-ray guidance, often with a cooled or strip-lesioning technique because the lateral branches are variable in their position. The endoscopic approach takes this further: through a small portal, the endoscope is passed to the region where the lateral branches run, and the nerves are ablated under direct, magnified vision. The rationale is that seeing the target, rather than relying on x-ray landmarks alone for nerves that vary from person to person, should allow a more complete and reliable interruption, and potentially more durable relief.

I am candid with patients about what an SI rhizotomy is and is not. It treats the pain from the joint; it does not repair or fuse the joint. The lateral branch nerves can regrow over time, so the relief, while it can last many months to a couple of years, is not always permanent and the procedure can be repeated. As with facet rhizotomy, its success depends heavily on getting the diagnosis right beforehand: it works well when the SI joint is genuinely the pain source and poorly when it is not, which is why diagnostic blocks matter so much. It is one part of a considered approach to SI joint pain, not a stand-alone cure, and I set those expectations honestly.

The evidence has two parts. For conventional radiofrequency lateral branch neurotomy of the SI joint, there is solid evidence — including several placebo-controlled randomised trials, with follow-up out to twelve months, and systematic reviews — that, in well-selected patients confirmed by diagnostic blocks, it provides meaningful and durable relief of SI-joint-mediated pain. The endoscopic-visualised technique is newer: systematic reviews and prospective cohorts of full-endoscopic SI joint denervation report it to be safe and effective with two-year outcomes, and a comparative study found navigation-assisted full-endoscopic rhizotomy gave greater improvement in pain and disability than cooled radiofrequency. I present it, therefore, as a refined, direct-vision option within a well-established treatment, always contingent on careful patient selection.

Endoscopic SI joint rhizotomy is a day-case, minimally invasive procedure. Most people go home the same day with a small dressing, and relief of the buttock and back pain typically settles in over the following days to weeks as the treated nerves quieten. Because the procedure targets pain rather than repairing the joint, the benefit is measured in months to a couple of years and can be repeated if the pain returns. As always, the plan is individualised and follows a careful diagnostic work-up.

• —Cohen SP, et al. Randomized placebo-controlled study of lateral branch radiofrequency denervation for sacroiliac joint pain. (PMC2666931)
• —Patel N, et al. Randomized, placebo-controlled study of lateral branch neurotomy for chronic sacroiliac joint pain. (PMID 22299761)
• —Patel N. Twelve-month follow-up of cooled radiofrequency denervation for sacroiliac region pain (RCT). (PMID 25565322)
• —Full-endoscopic sacroiliac joint denervation for chronic low back pain: systematic review. (PMC12945883)
• —Full-endoscopic sacroiliac joint denervation for painful SI joint dysfunction: prospective 2-year outcomes. (PMID 38916375)
• —Navigation-assisted full-endoscopic radiofrequency rhizotomy versus fluoroscopy-guided cooled radiofrequency for SI joint pain: comparative study. (PMID 37016862 / PMC10080431)
• —Radiofrequency ablation as long-term treatment for chronic sacroiliac joint pain: systematic review of RCTs. (PMC9311336)